/*
 * Copyright 2014 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkMatrix22_DEFINED
#define SkMatrix22_DEFINED

#include "include/core/SkPoint.h"

class SkMatrix;

/* * Find the Givens matrix G, which is the rotational matrix
 * that rotates the vector h to the positive hoizontal axis.
 * G * h = [hypot(h), 0]
 *
 * This is equivalent to
 *
 * SkScalar r = h.length();
 * SkScalar r_inv = r ? SkScalarInvert(r) : 0;
 * h.scale(r_inv);
 * G->setSinCos(-h.fY, h.fX);
 *
 * but has better numerical stability by using (partial) hypot,
 * and saves a multiply by not computing r.
 */
void SkComputeGivensRotation(const SkVector &h, SkMatrix *G);

#endif
